Erythrocytes, or red blood cells, have potential as carriers for drug delivery. They are biocompatible, biodegradable, have long circulation times, and can be loaded with drugs using various chemical and physical methods. Resealed erythrocytes are prepared by breaking open erythrocytes, loading them with drugs from solution, and resealing the cells. Various methods exist for drug loading, including hypotonic lysis, electroporation, and endocytosis. Loaded erythrocytes have applications in targeting drugs to tissues like the liver and spleen, and treating conditions like cancer, parasites, and iron overload. Further research continues to improve drug loading efficiency and stability of resealed

1. PRESENTED BY
V.SUHASINI
M.PHARM (PHARMACEUTICS)
RESEALED ERYTHROCYTES
1

2. INTRODUCTION
 Erythrocytes (RBCs) have potential carrier
capability for the delivery of drug
 Erythrocytes are biocompatible, biodegradable
possess long circulation half lives and can be
loaded with a variety of biologically active
compounds using various chemical and
physical methods
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3.  Carrier erythrocytes are prepared by collecting
blood sample and separating erythrocytes from
plasma. By using various methods
 1st the cells are broken and the drug is
entrapped into the erythrocytes, finally they
are resealed carriers are then called "resealed
erythrocytes".
 So many drugs like aspirin, steroid, cancer
drug which having many side effects are
reduce by resealed erythrocyte.
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4.  Erythro = red and cytes = cell
 Erythrocytes (RBCs) contain oxygen carrying
protein hemoglobin, which is a pigment that
gives whole blood its red color
 A healthy adult male has about 4.5 million
RBCs/μl of blood , and a healthy adult female
has about 4.8 million
 Immature RBC are called “RETICULOCYTES.
 So matured (RBCs) called erythrocyte have no
nucleus all their internal space is available for
oxygen transport
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5. biconcave
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6. Isolation of erythrocytes
 The cellular content is about 40-50% of the blood
volume and contains erythrocytes(red blood
cells,RBC),Leukocytes(while blood cells, WBC)
and thrombocytes (platelets).the primarily water
(90 to 92%) and protein(7%)
 Blood is collected into heparinized tubes by
venipuncture method
 withdrawn from cardiac case of small animal) and
through veins (in case large animals) into a
syringe
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7.  The whole blood is centrifuged at 2500 rpm
for 5 min at 40C in refrigerated centrifuge
 The serum and buffy coats are carefully
removed and packed cells washed for three
times with phosphate buffer saline pH=7.4
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8. Various animal erythrocytes used for
isolation
SR.NO SPCIES WASHING BUFFER CENTRIFUGAL
FORCE(G)
1 Rabbit 10mmol KH2PO4/NaHPO4 500-1000
2 Dog 15mmol KH2PO4/NaHPO4 500-1000
3 Human 154mmol NaCl <500
4 Mouse 10mmol KH2PO4/NaHPO4 100-500
5 Cow 10-15mmol KH2PO4/NaHPO4 1000
6 Horse 2mmol MgCl2,10mmol
glucose
1000
7 Sheep 10mmol KH2PO4/NaHPO4, 500-1000
8 Pig 10mmol KH2PO4/NaHPO4 500-1000
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9. ELECTROLYTE COMPOSITION
OF ERYTHROCYTES:
 Electrolyte are qualitatively similar to that of
plasma .however, quantitatively it differs from
that of plasma.
 The concentration of Na+ and K+ is more in
erythrocytes in plasma.
 The osmotic pressure of the interior of the
erythrocytes is equal to that of the plasma and
termed as isotonic (0.9% NaCl or normal
physiological saline.)
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10.  If the medium is Hypotonic, water diffuses into
the cells and they get swelled and eventually
loose all their hemoglobin content and may
burst.
 if the medium is Hypertonic,(i.e. higher
osmotic pressure than 0.9% NaCl) they will
shrink and become irregular in shape.
 Balanced ion solutions like Ringer’s and
Tyrode’s soln. which are not only isotonic but
also contains ions in proper quantity are used
in erythrocyte related experiments.
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12. Drug loading in erythrocytes
When erythrocytes are suspended in a
hypotonic medium they swell, and the
membrane rupture in the formation of pores
with diameters of 200 to 500 Å.
If the ionic strength of the medium then is
adjusted to isotonic and the cells are incubated
at 37ºC, the pores will close and cause the
erythrocyte to “Resealed”. Using this technique
upto 40% of drug can be entraped in the
resealed erythrocytes from the extracellular
solution. So, this systems are used for targeted
delivery via intravenous injection.
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13.  Normal aging erythrocytes, slightly damaged
erythrocytes, slightly damaged erythrocytes and
those coated lightly with antibodies are
sequestered in the spleen after intravenous vein
fusion, but heavily damaged or modified
erythrocytes are removed from the circulation by
the Liver.
Red cells
placed in
hypotonic
drug solutions
Lysis of cells
and entry of
drug
Resealed red
cells loaded
with drug
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14. ADVANTAGES OF ERYTHROCYTES AS
CARRIER
1. A remarkable degree of biocompatibility
2. Complete biodegradability and the lack of toxic
product resulting from the carrier biodegradation
3. Avoidance of any undesired immune responses
4. Considerable protection of the organism against
toxic effect of the encapsulation drug (e.g)
antineoplastic agent
5. Remarkably longer life span of the carrier
erythrocytes in circulation in comparison to the
synthetic carrier
 The entrapment of drug also does not require the
chemical modification of the substance to be entrapped
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16. DISADVANTAGES
 The rapid leakage of certain encapsulated
substances from the loaded erythrocytes
 Several molecules may alter the physiology of
the erythrocyte
 The storage of the loaded erythrocytes is a
further problem
 Possible contamination due to the origin of the
blood , the equipment used and the loading
environment
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18. VERIES METHOD OF DRUG
LOADING
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20. MEMBRANE PERTURBATION METHOD
 This method is based upon the increase in
membrane permeability of erythrocytes when
the cells are exposed to certain chemicals.
EX:
 It showed that the permeability of erythrocytic
membrane increases upon exposure to polyene
antibiotic such as amphotericin B.
 this method was used successfully to entrap
the antineoplastic drug daunomycin in human
and mouse erythrocytes .
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22. ELECTRO-INSERTION OR
ELECTROENCAPSULATION
 This method is also known as electroporation,
method
 Electrical breakdown is achieved by membrane
polarization for microseconds using varied
voltage of 2kv/cm is applied for 20 µsec.
 Electrolysis used to generate desirable membrane
permeability for drug loading .
 The extent of pore formation depends upon the
electric field strength, pulse duration and ionic
strength of suspending medium.
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23. - The compound which is to be entrapped was
added to the medium.
- After certain time the cell suspension was
transferred to a pre-cooled tubes and kept at
4ºC.
- Resealing of electrically perforated
erythrocytes membrane is then affected by
incubation at 37ºC in an osmotically
balanced medium.
- Major advantage is uniform distribution of
drug loading is achieved and possible to
entrap upto 35% of drug.
- Disadvantage is need sophisticated and
special instruments and time consuming.
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24. - The various drugs entrapped by this method include primaquine and related 8–
amino–quinolines,vinblastine, chlorpromazine and related phenothiazines,
hydrocortisone, propranolol, tetracaine, and vitamin A .
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25. HYPO OSMOTIC LYSIS METHOD
Dilution method:
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26.  Examples: hypotonic dilution is used for
loading enzymes such as galactosidase and
glucosidase, asparginase , as well as
bronchodilators such as sulbutamol
Limitations
1. Low entrapment efficiency and a
considerable loss of hemoglobin and other
cell components
2. Reduction in the circulation half life of the
loaded cells
3. Only for low molecular weight drug
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27. HYPO OSMOTIC LYSIS METHOD
Dialysis method:
- In this method, erythrocyte suspension +
Drug solution → dialysis tube and both ends
are tied with thread.
- This tube is placed in bottle containing
100ml of swelling solution at stored at 4ºC
for lysis.
- After, the dialysis tube is transferred to
100ml resealing solution (isotonic PBS, pH
7.4 ) at room temp. (25º-30ºC) for resealing.
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29. HYPO OSMOTIC LYSIS METHOD
Osmotic lysis:
- In this technique, haemolysis in isotonic solution
can be achieved by either chemical or physical
means or both.
- Erythrocytes are incubated in drug solution with
high trans erythrocytic membrane permeability
like PEG or NH4Cl or Urea which offers osmotic
diffusion until it reaches equilibrium.
- Then the solution was diluted with an isotonic-
buffered drug solution. These cell are separated,
washed and resealed at 37ºC.
 Eg: Dimethyl sulphoxide (DMSO),
monosaccharides, sucrose, etc.,
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31. HYPO OSMOTIC LYSIS METHOD
Preswell dilutional haemolysis:
- This technique is based upon initial controlled
swelling in hypotonic buffered solution.
- The principle involved in this technique is
swelling of erythrocytes without lysis by
placing them in slightly hypotonic solution and
centrifugation with low speed at 0ºC for 5min.
- To this add small volume of drug solution at
the point of lysis.
- This techniques results in retention of
cytoplasmic constituents and 72% of drug
entrapment.
Eg: Thyroxin, Ibuprofen, etc.,
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33. ENDOCYTOSIS METHOD:
- In this method, 1vol. of packed erythrocytes + 9 vol. of
buffer (containing 2.5mM ATP, 2.5mM MgCl2 and 1mM
CaCl2) and incubated for 2min at room temperature.
- The pores created in this method are resealed by using
154mM of NaCl and incubate at 37ºC for 2min.
- The entrapment of drug was obtained by endocytosis.
- the vesicle membrane separates endocytosed substance
from the cytoplasm and protect the erythrocyte
membrance.
Eg: 8-amino quinolines, Vinblastin, Chlorpromazine,
Phenothiazines, hydrocortison, propanolol, tetracine,
VitA, etc.,
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35. LIPID FUSION METHOD:
- Lipid vesicles containing a drug can be
directly fused to human erythrocytes, which
leads to an exchange with a lipid-entrapped
drug.
- Entrapment efficiency is very low (~1%).
Eg: Inositol monophosphate to improve the O2
carrying capacity of RBC.
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36. In vitro characterization
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37. In vitro characterization
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38. Shelf LifeAnd Storage Stability
 Encapsulated product and carrier both show
satisfactory self-stability when stored in
Hank’s balanced salt solution(HBSS)
example Potassium Phosphate at 4o C for
two weeks.
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39. APPLICATIONS OF RELEASED
ERYTHROCYTES
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40. Treatment of hepatic tumors: Antineoplastic drugs
like Methotrexate, Bleomycin, Asparginase and
Adrimycin delivered by RES.
Treatment of parasitic diseases: Antimalarial, and
antiamoebic
Removal of RES iron overload: Desferrioxamine,
an iron-chelating drug
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41. Conclusion
 Numerous applications have been proposed
for the use of resealed erythrocytes as carrier
for drug, enzymes replacement therapy etc
 Resealed erythrocytes technology will remain
an active area for further research
 Erythrocytes based delivery system with their
ability to provide controlled and site specific
drug delivery
 For the present it is concluded that erythrocyte
carriers are “GOLDEN EGGS IN NOVEL
DRUG DELIVERY SYSTEM”
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42. REFERENCES
 Targeted & controlled drug delivery , novel carrier
systems by S.P.VYAS & R.K.KHAR.
 Resealed Erythrocytes: A Novel Carrier for Drug
Targeting
Abhishek Kumar Sah, Ashish Rambhade, Alpna Ram and
Sunil K. Jain. J. Chem. Pharm. Res., 2011, 3(2):550-565
 http://pharmawiki.in/ppt-resealed-erythrocytes/
 http://www.ijrpc.com/files/04-355.pdf
 http://www.ijppsjournal.com/Vol4Issue3/4374.pdf
 http://ijpbs.net/volume2/issue1/pharma/_38.pdf
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